Gas Mining Technology and Application of Near Horizontal High Directional Drilling in Dongqu Coal Mine
Based on the problem of gas accumulation in the upper corner of the coal mine comprehensive mining face due to high mining intensity and gas emission,numerical simulation method and key layer control theory were used to study the development law of overlying rock fractures in the mining affected area.The optimal hole layout position and drilling structure for near horizontal high-level directional drilling were determined.Practice has shown that using near horizontal high-level directional drilling to extract gas,the maximum pure gas extraction volume of a single hole is 2.5 m3/min,and the total pure gas extraction volume of four boreholes is 345 000 m3.During the mining process,the gas concentration in the upper corner of the working face decreases to 0.31%,effectively solving the problem of gas exceeding the limit in the upper corner.
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